Production of diaryl alkanes



Patented Oct. 24, 1956 UNITED STATES PRODUCTION OF DIARYL ALKANESVladimir N. Ipatielf and Herman Pines, Chicago,

111., assignors to Universal Oil Products Company, Chicago, 111., acorporation of Delaware No Drawing. Application November 28, 1947,Serial No. 7885645 19 Claims.

This application is a continuation-in-part of our o-pending applicationSerial No. 619,430 filed September 29, 1945, now abandoned.

This invention relates to a process for producing a diarylalkane andparticularly for producing a diphenylalkane.

An object of this invention is to production of a diarylalkane.

Another object of this invention is the production of a diphenylalkanehydrocarbon.

A further obj eot of this invention is the production of alkyl diaryland cycloalkyl diarylalkane hydrocarbons.

A still further object of this invention is the production of an alkyldiphenylalkane. 1r

Additional objects of this invention are the production of l-p-tolyl-l-(-methyl-5-ethyl phenyD-ethane and l-p-tolyl-l-(2-methyl-5-npropylphenyl)-propane.

One specific embodiment of this invention relates to a process forproducing a diarylalkane hydrocarbon which comprises reacting athydrogen transfer conditions in the presence of an acidacting catalyst abranched chain olefin and an aromatic hydrocarbon having two hydrocarbonradical substituents in para position to each other and in which atleast one of these radicals has only two hydrogen atoms combined withthe carbon atom that is joined to the aromatic ring.

Another embodiment of this invention relates to a process for producinga diarylalkane hydrocarbon Which comprises reacting at hydrogen transferconditions in the presence of an acidacting catalyst an alkylcyclohexanehydrocarbon and an aromatic hydrocarbon having two hydrocarbon radicalsubstituents in para positions to each other and in which at least oneof these radicals has only two hydrogen atoms combined with the carbonatom that is joined to the aromatic ring.

A further embodiment of this invention relates to a process forproducing a diarylalkane hydrocarbon which comprises reacting athydrogen transfer conditions in the presence of an acidaoting catalyst abranched chain olefin and a benzene hydrocarbon of the formulahydrocarbon radical in which a oycloalkyl group replaces a hydrogen atomof an alkyl group. A cycloalkalkyl radical is thus a cycloalkylderivative of an alkyl radical.

We have developed a method of producin diarylalkanes by effecting ahydrogen transfer reaction between a branched chain olefinic hydrocarbonand an aromatic hydrocarbon containing at least two and generally notmore than five hydrocarbon radical substituents with two of thesesubstituents in para positions. Also at least one of said parasubstituents has only two hydrogen atoms combined with the carbon atomthat is joined to the aromatic ring. v

The essential reaction of this process is illustrated by the followingequationwherein a: is selected from 0 and the small even numbers, 2, 4,6, etc.

methyl-5-ethy1phenyD'-ethane from l-methyl-lethylbenzene andmethylcyclohexane is illustrated by the following equation:

Hydrogen transfer between l-methyl-i-npropylbenzene and a branched chainolefin such as methylcyclohexene takes place according to the followingequation to form 1-p-tolyl-1-(2- methyl-5-n-propylphenyl) -propane.

Similarly the production of 1-p-tolyl-1-(2 The reaction Of this processdiffers from those obtained by similarly treating a branched chainolefin and an aromatic hydrocarbon having two hydrocarbon radicalsubstituents in para positions to each other and in which each of theseradicals has only one or no replaceable hydrogen atom combined with thealpha carbon atom (that is, the carbon atom that is joined to thearomatic ring) and the aromatic hydrocarbon contains a replaceablenuclear hydrogen atom. When the mentioned hydrocarbon radical of thearomatic hydrocarbon has only one alpha hydrogen atom, a hydrogentransfer and a condensation occurs on contacting the aromatichydrocarbon and a branched chain olefin in the presence of an acidactingcatalyst to produce an indan hydrocarbon and to convert the branchedchain olefin into a branched chain saturated hydrocarbon. If thearomatic hydrocarbon being reacted with a branched chain olefin has noreplaceable hydrogen atom combined with the alpha-carbon atom of ahydrocarbon radical substituent, that is, if the substituent radical isa tertiary hydrocarbon group, such an aromatic hydrocarbon and abranched chain olefin in the presence of an acid-acting catalyst undergoan alkyl transfer reaction, but do not give a hydrogen transferreaction. Thus 1-methy1-4-tertiary-butylbenzene and methylcyclohexenereact in the presence of an acid-acting catalyst to form l-methyl-2A-ditertiary butylbenzene and l-methyl-4- (methylcyclohexyl) -benzene.

The aromatic hydrocarbon used in this process must contain at least onepara arrangement of hydrocarbon radical substituents in order to givethe hydrogen transfer reaction and yield a diarylalkane. Also one of thesubstituents in the para arrangerlent must contain only two hydrogenatoms combined with the carbon atom that is joined to the aromatic ring.Of such aromatic hydrocarbons suitable for the process, the benzenehydrocarbons may be represented by the formula:

wherein each of R and R is selected from the group consisting of analkyl radical, a cycloalkyl radical, a cycloalkalkyl radical and abicycloalkyl radical. The combination of the difierent R groups shouldbe balanced so as to avoid steric hindrance. Also aromatic hydrocarbonsand particularly benzene hydrocarbons containing more than threehydrocarbon substituent groups, may also be present in an aromatichydrocarbon charging stock provided that about 50 mole per cent of thearomatic hydrocarbons have a replaceable hydrogen atom combined with anuclear carbon atom. Thus the present process could utilize a highlyalkylated benzene, such as pentaethylbenzene for producingl-tetraethylphenyl-l- (2,3,4,5,6-pentaethylphenyl) -ethane or even amixture of about equal molecular proportions of hexaethylbenzene andpentaethylbenzene for producing 1 pentaethylphenyl 1(2,3,4,5,6-pentaethylphenyl) -ethane.

Suitable aromatic hydrocarbon starting materials include particularlyl-methyll-ethylbenzene, l-methyl-4-n-propylbenzene, 1,4-diethylbenzene,lA-di-n-propylbenzene, etc.

Olefinic starting materials suitable for this hydrogen transfer processhave branched chains and include such hydrocarbons as trimethylethylene,dihydrolimonene, methylcyclohexene, 1,1,3- trimethylcyclohexene,menthene, bicycloolefin, such as'camphene, etc. The exact type ofolefins to be used is dependent on the catalyst and the aromatichydrocarbon with which the hydrogen transfer is to be effected. Thusn-octene and cyclohexene, namely, olefins not possessing branchedchains, when reacted with a para-dialkylaromatic at operating conditionssimilar to those used with the branched chain olefins, effect alkylationbut not hydrogen transfer.

In addition to the branched chain monoolefins mentioned above, otherolefin-acting compounds which are also utilizable in this processcomprise conjugated diolefins containing a tertiary carbon atom,alcohols, ethers, esters of carboXylic acids, and alkyl halides whichmay be regarded as capable of forming branched chain olefins in situ inthe reaction mixture.

The process as herein described is carried out in the presence of anacid-acting catalyst at conditions necessary for the hydrogen transferreaction. Suitable acid-acting catalyst include mineral acids, such assulfuric acid, chlorosulionic acid, fiuorosulfonic acid, hydrogenfluoride, hYdrOXyBOl'OfillOllC acids, fiuorophosphoric acids, phosphoricacids and Friedel-Crafts halide catalysts, particularly aluminumchloride, aluminum bromide, ferric chloride, zirconium chloride, boronfluoride. Since in some cases Friedel-Crafts catalysts may cause analkyl migration within the aromatic ring before the hydrogen transferreaction occurs, it is sometimes advantageous to use Friedel-Craftscomplexes, such as etherate, alcoholate, etc., for this reaction.

Phosphoric acid catalyst comprises orthophosphoric acid and alsopolyphosphoric acids such as pyrophosphoric acid, triphosphoric acid,and tetraphosphoric acid. Under certain conditions of operation variousacid-acting, oxidetype catalysts may be used which include activatedclays, silica-alumina composites, and other silica-containing materialswhich are generally utilizable as catalysts for hydrocarbon cracking.

The operating conditions used in the process are dependent upon thenature of the hydrocarbons being treated and also upon the catalystsemployed. When utilizing strong mineral acids, such as hydrogenfluoride, sulfuric acid, fluorosulfonic acid, chlorosulfonic acid, andthe like, and also Friedel-Crafts metal halides promoted by a hydrogenhalide such as hydrogen chloride, the process is carried out at atemperature of from about --30 to about C. and at a pressure up to about100 atmospheres. However, in the presence of hydrogen fluoride, sulfuricacid, and aluminum chloride catalysts the preferred operatingtemperature is preferably from about 0 to about 50 C., while in contactwith ferric chloride catalyst the preferred operating temperature isfrom about 50 to about 100 C. Silica-alumina and other synthetic oxidecatalysts and clays are generally used at a temperature of from about200 to about 400 C., and at a superatmospheric pressure generally not inexcess of from about 100 atmospheres.

Our process is carried out in either batch or continuous type ofoperation. In batch type operation the usual procedure consists inplacing a mineral acid or Friedel-Crafts catalyst and a portion,generally about 50%, of the aromatic hydrocarbon in a reactor providedwith a mechanically driven stirrer, cooling these materials to atemperature of from about 0 to about C. and adding thereto withstirring, a solution of the branched chain olefin in the remainder ofthe aromatic hydrocarbon. The reaction mixture is then separated and theproduct is washed, dried, and distilled to recover therefrom thediarylalkane hydrocarbons. Unconverted aromatic hydrocarbons recoveredin this distillation are utilizable in the further operation of theprocess.

The process is also carried out in a continuous manner by passing thearomatic and cycloolefinic hydrocarbon through a suitable reactor inwhich they are contacted in the presence of the catalyst, the lattereither as a liquid or as a solid, depending upon the catalyst employedin the process. When using mineral acid catalysts such as sulfuric acid,chlorosulfonic acid, or hydrogen fluoride, this catalytic material isintroduced continuously to the reactor which is provided with suitablemixing means and the resultant product is then separated into ahydrocarbon layer and a catalyst layer, the latter being returned tofurther use in the process while the hydrocarbon layer is washed, dried,and distilled as hereinabove set forth. When a solid catalyst such assilica-alumina, clay, or a supported Friedel-Crafts type catalyst isused as a fixed bed in the reactor and. the aromatic and cycloolefinichydrocarbons are passed therethrough, the resultant hydrocarbon productrequires no washing and drying treatment and may be distilled toseparate therefrom unconverted aromatic and cycloolefinic hydrocarbonsand to recover the desired diarylalkane hydrocarbons.

In order to obtain relatively high yields of diarylalkane hydrocarbonsby our process, it is necessary to use rather carefully selectedhydrocarbon fractions as charging stocks. As already indicated herein,only certain types of aromatic hydrocarbons, namely those containingparticu-- lar substituents and readily replaceable nuclear hydrogenatoms are utilizable as starting materials to produce diarylalkanehydrocarbons.

Thus l-methyll-ethylbenzene and related alkyl-benzene hydrocarbons reactreadily with branched chain olefins to form a diphenylalkane and asaturated hydrocarbon, the latter having substantially the same carbonskeleton as that of the olefinic hydrocarbon charged to the process. Anaromatic hydrocarbon which does not contain the aforementionedhydrocarbon radical substituents in para positions to each other doesnot react with a branched chain olefin to give the desired hydrogentransfer reaction. Also an olefin which does not have a branched chainstructure such as is present in trimethylethylene, dihydrolimonene,methylcyclopentene, methylcyclohexene, etc., acts as an alkylating agentfor the aromatic hydrocarbon also charged to the process. Accordingly,in order to obtain hydrogen transfer reaction rather than alkylation, itis necessary to use a branched chain olefinic hydrocarbon together witha disubstituted benzene hydrocarbon or other disubstituted arylhydrocarbon in which substituents are in para positions to each otherand one of said substituents comprises an ethyl group, a normal propylgroup, or other hydrocarbon groups in which two'and only two hydrogenatoms are combined with the carbon atom adjacent to the aromaticnucleus, that is, the carbon atom in alpha position to the aromaticring.

The diarylalkane hydrocarbons resulting in this process may besulfonated and hydrolyzed to form phenols or they may be nitrated andreduced to the corresponding amines, suchamines may then be azotized andconverted into phenols which may be useful as inhibitors to retardoxidation of hydrocarbons, fats, vegetable oils, foods, etc. Thesulfonation product of a diarylalkane containing a long alkyl,cycloalkalkyl, or cycloalkyl group may also be converted into asurfaceactive agent such as a wetting agent or detergent. Some of thediarylalkane hydrocarbons formed in this process may also be useful asadditives in lubricating oils.

The following examples are given to illustrate the character of resultsobtained by the use of specific embodiments of the present invention,although the data presented are not introduced with the intention ofunduly restricting the generally broad scope of the invention.

Example I A copper reactor equipped with a motor-driven stirrer andprovided with a dropping funnel was immersed into an ice bath (0 C.)Into the flaskshaped reactor was placed 25 grams of substantiallyanhydrous hydrogen fluoride and 120 (0.1 mole) ofl-methyll-ethylbenzene. The mixture was stirred and to it was added overa period of 45 minutes, a solution consisting of 120 grams (1.0 mole) ofl-methyll-ethylbenzene and 96 grams 1.0 mole) of 4-methylcyclohexene.The reaction mixture was stirred continuously for an additional time of30 minutes and the reaction mixture was then poured into ice,,thehydrocarbon layer was separated, dried and distilled. The productsrecovered from the reaction mixture consisted of methylcyclohexane, 43g. (0.45 M) B. P. 100-105; l-methyll-ethylbenzene, 94 g. (0.80 M) B. P.85-87/ 60 mm. l-methyll-ethyl- -X-(methyl-cyclohexyl)-benZene, 59 g. B.P.,

129/8 mm.; and l-p-tolyl-l-(2-methyl-5-ethylphenyl)-ethane, 77 g. (0.33M). B. P.

- 0H3 EH: I l H y H- CH3 Emample II A similar reaction was carried outin which 48 grams (0.4 mole) of l-methyll-ethylbenzene and 20 grams (0.2mole of methylcyclohexene were reacted in the presence of 36 grams ofsulfuric acid of 96% E804 concentration. The results of this run weresimilar to those of EX- ample I. Thel-p-tolyl-l-(2-methyl-4-ethylphenyD-ethane had a refractive index n of1.554. Nitration of this hydrocarbon yielded a tetranitroderivativecorresponding to the formula C18H1GN408 as evidenced by its determinednitrogen content of 13.65 weight per cent, which compared favorably witha nitrogen content of 13.86 weight per cent calculated on the basis ofthe foregoing formula. The l-p-tolyl-l-(Z-methyl- 5-ethylphenyl-ethaneformed in this process was identical with a synthetically preparedsample of this hydrocarbon.

Example III benzene were placed in a copper flask equipped with amechanically driven stirrer and surrounded by an ice bath C.). To amixture of 26 grams of anhydrous hydrogen fluoride and 26.8 grams (0.2mole) of 1-methyl-4-n-propylbenzene was added dropwise during a periodof one-half hour a total of 10 grams (0.1 mole) of methylcyclohexene.After all of the methylcyclohexene had been added, the reaction mixturewas stirred for an additional time of 30 minutes and then poured upon'75 grams of ice precooled to -30 C. The hydrocarbon oil layer as thenseparated from the aqueous layer and the former was washed with water,dilute potassium hydroxide solution, again with water, and dried toyield 33 grams of a dry hydrocarbon mixture. Distillation of thehydrocarbon mixture through a 30 centimeter distilling column containingnichrome wire spiral packing gave the fractions with the followingboiling points and refractive 1nd1ces:

Boiling Point Fraction Grams no be At mm. Hg

748 3.2 1.4248 748 1.1 1.4581 148 7.4 1.4920 23 3.8 1.4938 4 1.2 1.48834 3.1 1. 5230 4 2.3 1.5342 4 5.6 1. 5445 4 1.1 1. 5433 Residue 2.

The material present in fractions 1 and 2 corresponded tomethylcyclohexane formed by the hydrogen transfer reaction. Fractions 4and 5 consisted of unconverted 1-methyl-4-n-propylbenzene. Fractions '7and 8 consisted of cycloalkylated l-methyl 4 n-propylbenzene. Fractions9 and 10 consisted of 1-p-tolyl-l-(2-methyl- 5-n-propylphenyl) propane.Analysis of fraction 9 showed 90.31% by weight of carbon and 9.93% byweight of hydrogen, these values corresponding closely to 90.16% byweight of carbon and 9.84% by weight of hydrogen calculated for ahydrocarbon of the formula CH26.

The infrared absorption spectrum of fraction 9 was identical with theinfrared absorption spectrum of synthetically prepared l-p-tolyl-l-(2-methyl-S-n-propylphenyl) -propane.

We claim as our invention:

1. A process for producing an unsymmetical diarylalkane hydrocarbonwhich comprises reacting at hydrogen transfer conditions in the presenceof an acid-acting catalyst a branched chain olefin-acting compound andan aromatic hydrocarbon having a replaceable nuclear hydrogen atom andtwo hydrocarbon radical substituents in para position to each other andin which at least one of said radical substituents has only two hydrogenatoms combined with the carbon atom that is joined to the aromatic ring.

2. A process for producing an unsymmetrical diarylalkane hydrocarbonwhich comprises reacting at hydrogen transfer conditions in the presenceof an acid-acting catalyst a branched chain olefin and an aromatichydrocarbon having a replaceable nuclear hydrogen atom and twohydrocarbon radical substituents in para position to each other and inwhich at least one of said radical substituents has only two hydrogenatoms combined with the carbon atom that is joined to the aromatic ring.

3. A process for producing an unsymmetrical diarylalkane hydrocarbonwhich comprises reacting at hydrogen transfer conditions in the presenceof an acid-acting catalyst an alkylcyclohexane hydrocarbon and anaromatic hydrocarbon having a replaceable nuclear hydrogen atom and twohydrocarbon radical substituents in para position to each other and inwhich at least one of these radicals has only two hydrogen atomscombined with the carbon atom that is joined to the aromatic ring.

4. A process for producing an unsymmetrical diarylalkane hydrocarbonwhich comprises reacting at hydrogen transfer conditions in the presenceof an acid-acting catalyst a branched chain olefin and a benzenehydrocarbon of the formula wherein each of R and R is selected from thegroup consisting of an alkyl radical, a cycloalkyl radical, acycloalkalkyl radical, and a bicycloalkyl radical.

5. A process for producing an unsymmetrical diarylalkane hydrocarbonwhich comprises reacting in the presence of a mineral acid catalyst at atemperature of from about 30 to about C. a branched chain olefin and anaromatic hydrocarbon having a replaceable nuclear hydrogen atom and twohydrocarbon radical substituents in para positions to each other and inwhich at least one of said radical substituents has only two hydrogenatoms combined with the carbon atom that is joined to the aromatic ring.

6. A process for producing an unsymmetrical diphenylalkane hydrocarbonwhich comprises reacting in the presence of a mineral acid catalyst at atemperature of from about 30 to about 100 C. a branched chain olefin anda benzene hydrocarbon having a replaceable nuclear hydrogen atom and twohydrocarbon radical substituents in para positions to each other and inwhich at least one of said radical substituents has only two hydrogenatoms combined with the carbon atom that is joined to the aromatic ring.

7. A process for producing an unsymmetrical diphenylalkane hydrocarbonwhich comprises reacting in the presence of a mineral acid catalyst at atemperature of from about 30 to about 100 C. an alkyl cycloolefin and abenzene hydrocarbon having a replaceable nuclear hydrogen atom and twohydrocarbon radical substituents in para positions to each other and inwhich at least one of said radical substituents has only two hydrogenatoms combined with the carbon atom that is joined to the aromatic ring.

8. A process for producing an unsymmetrical diphenylalkane hydrocarbonwhich comprises reacting in the presence of a sulfuric acid catalyst ata temperature of from about 0 C. to about 50 C. an alkylcycloolefin anda benzene hydrocarbon having a replaceable nuclear hydrogen atom and twohydrocarbon radical substituents in para positions to each other and inwhich at least one of said radical substituents has only two hydrogenatoms combined with the carbon atom that is joined to the aromatic ring.

9. A process for producing an unsymmetrical diphenylalkane hydrocarbonwhich comprises reacting in the presence of a hydrogen fluoride catalystat a temperature of from about -30 to about 100 C. a branched chainolefin and a benzene hydrocarbon having a replaceable nuclear hydrogenatom and two hydrocarbon radical substituents in para positions to eachother and in which at least one of said radical substituents has onlytwo hydrogen-atoms combined with the carbon atom that is joined to thearcmatic ring.

10. A process for producing an unsymmetrical diphenylalkane hydrocarbonwhich comprises reacting in the presence of a hydrogen fluoride catalystat a temperature of from about 30 to about 100 C. an alkylcycloolefinand a benzene hydrocarbon having a replaceable nuclear hydrogen atom andtwo hydrocarbon radical substituents in para positions to each other andin which at least one of said radical substituents has only two hydrogenatoms combined with the carbon atom that is joined to the aromatic ring.

11. A process for producing an unsymmetrical diphenylalkane hydrocarbonwhich comprises reacting in the presence of a hydrogen fluoride catalystat a temperature of from about 30 to about 100 C. an alkylcyclohexeneand a benzene hydrocarbon having a replaceable nuclear hydrogen atom andtwo hydrocarbon radical substituents in para positions toieach other andin which at least one of said radical substituents has only two hydrogenatoms combined with the carbon atom that is joined to the aromatic ring.

12. A process for producing l-p-tolyl-l-(Z- methyl-S-ethylphenyl)-ethane l which comprises reacting 1 methyl 4 ethylbenzene and abranched chain olefin in the presence of a mineral acid catalyst at atemperature of from about 30 to 100 C. I

13. A process for producing 1-p-t01y1-1-(2- methyl-S-ethylphenyl)-ethanewhich comprises reacting 1-methyl-4-ethylbenzene and a methylcyclohexenein the presence of a sulfuric acid catalyst at a temperature of fromabout to about 50 C.

14. A process for producing 1-p-t0ly1-1-(2- methy1-5-ethylphenyl)-ethanewhich comprises reacting l-methyl-l-ethylbenzene and methylcyclohexenein the presence of a hydrogen fluoride catalyst at a temperature of fromabout 0 to about 50 C.

15. A process for producing l-p-tolyl-l-(Z-methyl-5-n-propy1phenyl)-propane which comprises reacting1-methyl-4-n-propylbenzene and methylcyclohexene in the presence of ahydrogen fluoride catalyst at a temperature of from about 0 to about 50C.

16. A diarylalkane hydrocarbon represented by the formula REFERENCESCITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,939,932 Thomas Dec. 19, 19332,246,762 Schirm June 24, 1941 OTHER REFERENCES Simons, Potential Use ofHydrogen Fluoride in Organic Chemistry Processes, Ind. Eng. Chem., vol.32, No. 2, pages 178-183 (6 pages) (February 1940).

1. A PROCESS FOR PRODUCING AN UNSYMMETICAL DIARYLALKANE HYDROCARBONWHICH COMPRISES REACTING AT HYDROGEN TRANSFER CONDITIONS IN THE PRESENCEOF AN ACID-ACTING CATALYST A BRANCHED CHAIN OLEFIN-ACTING COMPOUND ANDAN AROMATIC HYDROCARBON HAVING A REPLACEABLE NUCLEAR HYDROGEN ATOM ANDTWO HYDROCARBON RADICAL SUBSTITUENTS IN PARA POSITION TO EACH OTHER ANDIN WHICH AT LEAST ONE OF SAID RADICAL SUBSTITUENTS HAS ONLY TWO HYDROGENATOMS COMBINED WITH THE CARBON ATOM THAT IS JOINED TO THE AROMATIC RING.